70% of Mexican crime scene weapons reported to have originated in US

On 12 January 2016, Mother Jones reporter Bryan Schatz wrote an article on a recent Government Accountability Office (GAO) report that claimed that 70 percent of the guns recovered from Mexican crime scenes between 2009 and 2014 had originated in the United States, as traced by the Bureau of Alcohol, Tobacco, Firearms and Explosives (ATF).

The article reported that the recovered guns were often bought legally in the US (in shops, gun shows, or though private sales). However, cartels are increasingly shipping weapon parts across the border into Mexico to be reassembled into functional firearms. This transfer is difficult to detect. For instance, cartel gunrunners often use receivers that are 80% finished but require final machining in order to become operational; in the US, such unfinished receivers are not classified as firearms.

Collaboration between Mexican and US officials is also problematic: US officials have expressed concern over high corruption amongst their Mexican counterparts, which limits the information that US Immigration and Customs Enforcement (ICE) officials are willing to share with Mexican authorities.

Nonetheless, the report highlights that a huge number of US guns are used in Mexican murders – of which many are mass shootings.